An asteroid is commonly believed to be responsible for the mass extinction that wiped out the dinosaurs around 65 million years ago, but a new study points out another possible cause.
A team of researchers in Japan argues that the Earth's prolonged collision with a dense, dark cloud provides a better explanation for the catastrophic event.
They believe that global cooling occurred as a result which, New Scientist reports, "would also have destroyed the ozone layer and halted photosynthesis."
This Nebula Winter, as the team calls it, would have also led to an enlarged continental ice sheet with exposed continental shelves and reduced marine areas.
See photos of dinosaur fossils below:
The basis for this conclusion is a 16-foot-deep section of iridium found deep in the sea floor; the element is rare on Earth but could be produced after contact with such "a giant molecular cloud."
Overall, the researchers have stated that the change in "global climate [is] a more plausible explanation for the mass extinction than a single impact event."
Some scientists are not yet convinced of the findings, but one NASA expert says additional proof could be uncovered.